Roll Dart SDK from b8b4076b1237 to 2a1a13cc3a91 (1 revision) (#166504)

https://dart.googlesource.com/sdk.git/+log/b8b4076b1237..2a1a13cc3a91

2025-04-02 dart-internal-merge@dart-ci-internal.iam.gserviceaccount.com
Version 3.8.0-258.0.dev

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dart-sdk-flutter
Please CC aaclarke@google.com,dart-vm-team@google.com on the revert to
ensure that a human
is aware of the problem.

To file a bug in Flutter:
https://github.com/flutter/flutter/issues/new/choose

To report a problem with the AutoRoller itself, please file a bug:
https://issues.skia.org/issues/new?component=1389291&template=1850622

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md

DEPS

@@ -56,12 +56,12 @@ vars = {
   # Dart is: https://github.com/dart-lang/sdk/blob/main/DEPS
   # You can use //tools/dart/create_updated_flutter_deps.py to produce
   # updated revision list of existing dependencies.
-  'dart_revision': 'b8b4076b12378af3a4ecfd07fa41524c1fdf9b65',
+  'dart_revision': '2a1a13cc3a9167da547869d6ec15f2fa16b1dde2',
 
   # WARNING: DO NOT EDIT MANUALLY
   # The lines between blank lines above and below are generated by a script. See create_updated_flutter_deps.py
   'dart_binaryen_rev': 'b4bdcc33115b31758c56b83bb9de4642c411a042',
-  'dart_boringssl_rev': 'a9993612faac4866bc33ca8ff37bfd0659af1c48',
+  'dart_boringssl_rev': 'c86127e656ae8b95622c79ba3d0fb35415502d53',
   'dart_core_rev': 'a6e81e0b74faf12ed4a938fa9a8ddba86b89b73d',
   'dart_devtools_rev': 'f10e8df8c517fb0412b9a66c626581867c9c267d',
   'dart_ecosystem_rev': '391a80ccb774cfebe4865bcd7e933d1ab016eea5',